According to statistics compiled since 1990 by the National Fire Protection Association, one third of firefighters who died of smoke inhalation while fighting a fire within a burning building perished because they became lost within the building and their breathing apparatus ran out of air before they could find their way back out. The loss of situational awareness by firefighters within a burning building, even among the most experienced firefighters with the best training, is likely unavoidable in view of the extremely dangerous environment of intense heat and flames, blinding smoke and falling debris encountered while fighting a fire and effecting rescue of persons trapped in a burning building.
This problem of firefighters becoming lost within burning structures such as buildings, aircraft, ships, oil platforms and the like has been addressed in the past by the use of search lines which are carried by the firefighter into the burning structure. One end of the line is secured outside of the entrance to the structure, the other end remains secured to the firefighter and is payed out as he or she moves through the structure. The line allows the firefighter to find the way back to safety through the maze of burning debris and flames despite the blinding smoke within the structure. The line also allows other firefighters to locate comrades who may be injured or trapped by debris and unable to move from a deteriorating situation. The line may also be used to find the remains of firefighters killed in the line of duty.
Search lines are, thus, seen to be a vital piece of safety equipment and, if used, could prevent a substantial number of deaths in fighting fires. To be effective, search lines should be able to withstand the intense heat of a building fire while remaining strong and flexible so as to remain intact and lead the firefighter back to safety. The search line should also be resistant to cuts and abrasions occasioned by falling debris within the burning structure as well as by friction between the line and parts of the structure around which the line may be bent or drawn.